The present invention relates to forceps, and more particularly to forceps for mounting on a flexible guide wire so as to obtain a specimen from the biliary or pancreatic system for Endsoscopic Retrograde Cholangeopancreatography (ERCP) evaluation.
ERCP was originally introduced as a diagnostic radiologic study of the biliary and pancreatic systems that took advantage of endoscopic ampullary access for contrast injection. Today, it is carried out to perform a variety of pancreatico-biliary diagnostic and therapeutic maneuvers. The demand for rapid and accurate ERCP diagnosis has increased, particularly in conditions that involve biliary strictures. It has been reported that the diagnostic sensitivity of a cholangiopancreatogram for pancreatic carcinoma is between 62% to 92%. False positive ERCP studies in diagnosing ductal malignancy, however, may be significant. Of particular concern is mistaken interpretation of biliary strictures, which may arise from benign as well as malignant processes. Thus it is suboptimal to base a therapeutic decision solely on crude, though valuable, ERCP findings. Naturally, this leads to the search for a biliary tissue sampling method that would improve the diagnostic accuracy of cholangiopancreatography.
There are many available methods to sample biliary strictures during ERCP.
(A) CYTOLOGIC METHODS:
Aspiration of obstructed bile fluid PA1 Simple brushing of biliary stricture PA1 Brushing via a "guided" system PA1 Submucosal needle aspiration of obstructive PA1 lesion PA1 Stent cytology PA1 Scrape cytology PA1 Forceps biopsy--X-ray guided PA1 Forceps biopsy--cholangioscopically guided PA1 Submucosal needle aspiration biopsy PA1 Scrape biopsy
(B) BIOPSY/HISTOLOGIC METHODS:
Each of these methods has its own limitations, restrictions, and difficulties such that no one technique is always preferable to another. Thus, some methods require additional maneuvering after the successful passage of a catheter through the biliary structure, some involve the use of such large caliper instrumentation that there may be some difficulty in passing through tight strictures, some are too harsh and may cause ductal perforation and excessive trauma to the stricture, or perforation of the bile duct. Nonetheless, it is generally considered that forceps biopsy should always be performed because it provides a superior yield of severed tissue compared to other methods. A unique advantage of forceps biopsy over all cytological methods is its ability to identify polyps, fibrosis and other benign tissue changes.
The forceps useful in biliary or pancreatic systems is necessarily substantially flexible. In other words, while the actual tip of the forceps may be substantially rigid (for a length of about 1-2 cm), the remainder of the forceps (which generally extend 200-220 cm) is necessarily highly flexible in order to enable the forceps, once it emerges from the lumen of the endoscope, to follow the tortuous path leading to the biliary duct tree. Nonetheless, great care must be taken during insertion of the forceps to make sure that it travels the desired route or travel path as it is being advanced distally beyond the endoscope. While the intermediate and final positions achieved by the forceps may be determined through x-rays, fluoroscopy, or cholangioscopy for proper execution, the insertion process is necessarily slow and tedious due to the relatively large width of the forceps, typically about 1.8-2.3 mm.
Accordingly, it is an object of the present invention to provide forceps which may be easily and rapidly advanced beyond the endoscope into the biliary tree.
Another object is to provide such forceps which are mounted on a substantially flexible, relatively thin guide wire which has been inserted beyond the endoscope into the biliary tree so that the forceps may be easily and rapidly advanced therealong.
It is a further object to provide such forceps which are easy and economical to manufacture, maintain and use.